This application claims the benefit of U.S. Provisional Application No. 60/609,745, filed on Sep. 14, 2004. The disclosure of the above application is incorporated herein by reference.
The present invention relates generally to safety restraint systems for motor vehicles. More specifically, the present invention is directed to an improved seat belt retractor having both ELR and ALR functionality.
As known in the art, ELR means an emergency locking retractor, which typically includes one or more inertial locking mechanisms, as more particularly illustrated in European Patent application EP0228729A1, which is incorporated herein by reference. The typical ELR seat belt retractor includes both a vehicle sensitive locking mechanism and a web sensitive locking mechanism. Often the vehicle sensitive locking mechanism and the web sensitive locking mechanism share common parts, which results in a more cost-effective seat belt retractor.
Quite often, the vehicle sensitive locking mechanism includes a first housing member that is rotationally mounted relative to a side of the retractor frame as well as to the retractor spool. This first housing member is called, in some literature, a lock cup. This first housing member supports a movable inertial mass configured as a ball or standing man. Sudden acceleration or acceleration in excess of a first limit value or severe rotation beyond a limit of the vehicle value causes movement of this inertial mass, which initiates lockup of the retractor. The first housing member typically includes a rotationally supported pawl, also referred to as a sensor pawl since it cooperates with the inertial mass. Movement of the inertial mass causes movement of the sensor pawl from a deactivated position to an activated position.
In the activated position the inertial pawl engages one or more teeth of a ratchet wheel; the ratchet wheel is loosely supported for rotation about the rotational axis of the spool and rotationally movable with the retractor spool. The engagement of the sensor pawl with the ratchet wheel links the ratchet wheel to the spool, which causes the lock cup member to rotate with the rotating spool. The rotation of the lock cup in concert with the rotation of the spool causes a lock pawl to move into engagement with the one or more teeth of another ratchet wheel (also referred to as a lock wheel). The lock wheel and the ratchet wheel that cooperates with the sensor pawl can be the same part. Engagement of the lock pawl with the teeth of the lock wheel leads to the initial lockup of a typical seat belt retractor.
When the seat belt tongue is removed from a cooperating seat belt buckle, the extended seat belt (also called seat belt webbing or webbing) will be retracted onto the spool in response to a bias force typically provided by a rewind spring of known construction. The rewind spring will rewind all of the available seat belt webbing onto the spool, so that the seat: belt retractor is ready for its next use cycle. This condition is typically called the stowed condition, as the seat belt webbing is now stowed or rewound onto spool. In this mode of operation it is anticipated and often required that the ELR locking mechanisms are in a deactivated condition so that the seat belt webbing is free to be extended (protracted) or retracted without intervention of the ELR locking mechanisms, that is the vehicle sensitive or web sensitive locking mechanisms. Occasionally, as reported in literature, as the seat belt webbing is moved to the stowed position, the vehicle sensitive locking mechanism inadvertently will assume an undesirable locked condition, which prevents the seat belt from being easily extended from the retractor. Fortunately this condition is usually temporary. This is an undesirable condition, which is avoided in the present invention by biasing the sensor pawl, when the seat belt is in a stowed condition, away from the ratchet wheel, preventing such an inadvertent lock condition of the retractor. Also, if the retractor is mounted in a movable seat back, this feature will prevent the retractor from locking up as the seat back is moved.
As mentioned, it is also commonplace for an emergency locking seat belt retractor to include ALR functionality. When in the ALR mode of operation, the vehicle sensitive and web sensitive locking functions are bypassed. As known by those skilled in the art, ALR functionality of the seat belt retractor is typically activated as the seat belt webbing is secured about a child seat. As also known by those skilled in the art, the acronym ALR stands for automatically locking retractor. In most situations, to activate the ALR mode of operation, most if not all of the seat belt webbing is manually pulled out or protracted from the spool prior to the seat belt being placed about a child seat. Then the seat belt is released to envelop the child seat. As the last section of seat belt webbing is protracted from the spool, the prior art retractor enters its automatic locking mode (ALR) mode of operation.
ALR mechanisms often include one or more gear devices, which rotate with the retractor spool and which provide an effective measurement of the length of webbing that has been removed from the spool. As the webbing is pulled from the spool, the ALR mechanism typically presents a mechanical feature, which causes the retractor to enter into its automatic locking mode of operation. For example, the one such ALR mechanism as shown in U.S. Pat. No. 5,904,371, which is incorporated herein by reference, selectively biases an ALR pawl into engagement with a ratchet wheel on extension of the last section of the seat belt. Biasing the ALR pawl into the ratchet wheel initiates retractor lockup as provided by the vehicle sensitive locking mechanism. The seat belt retractor will remain in its ALR mode of operation as the length of protracted webbing is rewound on the spool and will return the retractor to its ELR mode of operation upon full retraction of the belt.
The ALR mechanism in the above-referenced patent includes a spring-loaded lever that is physically maintained out of engagement with the ALR pawl. More specifically, the spring-loaded member is biased onto an edge of a cam disk that rotates with the spool. After a predetermined number of spool rotations corresponding to the removal of virtually all of the webbing from the spool, the cam disk is rotated into a position to present a notch to the spring-loaded lever. Thereafter the spring-loaded lever falls into the notch, engages a surface of the ALR lever and moves the ALR pawl into engagement with one of the teeth of the ratchet wheel to initiate lock-up of the retractor.
In the present invention a single lever, in cooperation with other components, is used to control the locking mode (ELR/ALR) of the seat belt retractor. When the seat belt is fully stowed on the retractor spool, the lever is moved to a position that biases a sensor pawl upon a vehicle inertia mass to effectively block out the ELR mode of operation. Upon protraction of a small yet determinable amount of webbing, the retractor enters into an ELR mode of operation. During its normal mode of use, such as with some of the seat belt webbing protracted about the occupant, the retractor will remain in the ELR mode of operation, however, the ALR mode of operation is not accessible until after all of the seat belt has been pulled from the retractor.
This extension of the seat belt occurs when the seat belt is being placed, for example, about a child seat. In the ELR mode of operation the lever is displaced from the sensor pawl, and the sensor pawl and the vehicle inertia mass are permitted to move in response to vehicle dynamic conditions. In the ALR mode of operation the lever biases the sensor pawl into a cooperating ratchet wheel. The change into the automatic locking mode (ALR) is effective not upon the protraction of the last section of seat belt webbing but upon the initial angular rotation of the spool, in the direction of retraction from the fully protracted condition. Entering into the ALR mode of operation at the beginning of seat belt retraction causes less strain on the sensor pawl than when initiating the ALR mode on the full extension of the webbing.
It is an object of the present invention to provide an improved seat belt retractor.
Accordingly the invention comprises: a seat belt retractor having ELR and ALR modes of operation. The retractor comprises a sensor pawl movable between a release and a locked position with one or more teeth of a ratchet wheel rotatable with a spool of the retractor; the sensor pawl forms part of both ELR and ALR locking mechanisms. A spring biased first lever is movable between various positions in which the sensor pawl is enabled or disabled to effect ELR block-out, ELR operation and ALR operation. The lever is rotatable to a first position and when in the first position urges the sensor pawl toward engagement with the ratchet wheel, permitting ALR operation. The lever is movable to a second position, which urges the sensor pawl away from the ratchet wheel teeth thereby preventing the retractor from entering into its ELR mode of operation. The lever, when in its second position, biases the sensor pawl into engagement with a cooperating inertial mass that is part of a vehicle sensitive locking mechanism of the seat belt retractor. This bias force (operative on the sensor pawl) is effective to limit the motion of the inertial mass to lessen or eliminate vibrational movement of the inertial mass relative to the sensor pawl (as well as movement of the sensor pawl) and movement relative to a support basket or support structure that,holds the inertial mass, thereby lessening acoustic and vibrational noise created by the movement and rattling of the sensor pawl and/or inertial mass. When the lever is in a mid-position the sensor pawl and vehicle mass are free to move and the retractor is in its ELR mode of operation.
Many other objects and purposes of the invention will be clear from the following detailed description of the drawings.